What about Keratin therapy?
Have you thought about Brazalian Keratin Therapy treatment? You can buy the kit from a drug store and do it yourself at home. I did it a while back and it actually made my hair healthier! The ad says it's a 30-day treatment, but mine lasted for 3 months and I LOVED it. I did not have to use a flattening iron after I did this, my hair was wash and go and still stayed straight. The only drawback is the time you have to let the stuff sit on your hair without putting it in a ponytail or washing it (72 hrs.). The process involves you putting the stuff in your hair and then flat ironing each section, so it's a fairly long process if you have long hair. Just a thought though just in case you didn't know about this.
Fine/3a-c hair, CG since 2006
C/O wash: Suave Waterlily Aloe, As I am Coconut Co-wash
Stylers: Kinky Curly Custard Cream, Kinky Curly Knot Today Detangler,Herbal Essence Set me Free Gel, Lily of the Desert 99% Aloe Vera Gelly
HG: Neutral protein filler
DT: Coconut Oil, Argan Oil
Special Considerations: I frequently color because I have almost 50% grey, I use a semi-permanent to reduce damage